Stuart Staniford has a WONDERFUL post about what I think is the most likely scenario – we finally acknowledge the (obvious, scientifically clear) reality of climate change and panic, and try and fix it…having waited too long. He asks…what might that look like? He’s not shooting for perfect accuracy here, just some general scenarios, and I think he comes to what is generally the right conclusion, always barring the real but harder to model possibility of a non-linear change;
The red curve shows what happens if we wait another decade – until 2030 – to start bending the emissions curve, with emissions then peaking in 2040. Now, atmospheric CO2 doesn’t peak until around 2065, at a level almost double the pre-industrial concentration. Very scary.
By contrast, the yellow curve shows what happens if we start to bend the curve now and manage to constrain emissions to peak in 2020. That results in a concentration peak in 2040 at about 440ppm. Still pretty bad – we have already left it late to act. Nonetheless, I consider the yellow curve to be unrealistically optimistic – I don’t see signs that the world is taking the issue seriously enough to cause an imminent reduction in the growth rate of carbon emissions this year or next.
It’s worth emphasizing that the exact details of these scenarios are not likely to prove accurate – how long it takes for emissions to peak after starting to reduce the growth rate, how fast we will be able to get negative, and how negative, are all uncertain. These are generally indicative rather than precisely accurate.
It’s also worth noting that peak temperature is likely to be decades after peak atmospheric carbon. So, from the point we start to get really serious, it will then be around fifty years until peak temperature. Dealing with this is going to be a life-long effort for all of us, and all of our children and grandchildren.
The larger point is – however late we’ve left it to act, it’s always possible to make it much worse by waiting even longer.
His last point bears repeating several times. There is a tendency to either deny that we’ve left it too late (ie, minimize) or to claim that having waited so long, there’s no point in doing anything. Neither of those is correct, and it is simply time to acknowledge it and work with what we’ve got.